Scientists have created mice with two fathers. A surrogate mother is required, but her DNA isn't passed to the selected offspring.. (Source: Science Museum)

The laws of nature are being seriously bent by this Texas team

Two male mammals can not reproduce with each other, right? That's what you learned in your biology class, certainly. Well turns out, like many laws of nature, there can be exceptions, with a certain amount of trickery. Researchers at the M.D. Anderson Cancer Center in Houston, Texas have bent the rules of mammalian biology and created a pair of mice, one male one female, that have two fathers and no maternal sex chromosomes.

The MDACC team of reproductive biologists, led by Dr. Richard R. Berhringer first took fibroblasts (connective tissue cells) from the first male (XY) father mouse, when he was just a fetus. The fibroblasts were selected as they are easy to induce into pluripotency, a method of producing non-embryonic stem cells. The induced pluripotent stem cells (iPSCs) were then cultured.

During the culturing something funny happened -- the Y allele disappeared in some of the cells. This proved a critical step in producing two-father babies. The XO cells were then transplanted into the blastocyst (developing embryo) of a mouse surrogate mother. The resulting female chimera children (a second surrogate mother), which had a mix of XO/XX sex chromosomes. The females (which bore the paternal chromesome from the first father) were then mated with the second father.

The end result of this rather confusing process was that some of the children had sex chromosomes from both fathers, or both mothers. They also likely inherited autosomes from each father.

The team proclaims, "Our study exploits iPS cell technologies to combine the alleles from two males to generate male and female progeny, i.e. a new form of mammalian reproduction."

The researchers speculate that they could also use the technique to get the mouse to self reproduce. They state, "It is also possible that one male could produce both oocytes and sperm for self-fertilization to generate male and female progeny."

They say that it could be leveraged to save endangered species. If only two males were in captivity, a surrogate mother of a similar species could be used to birth a Chimera which would produce oocytes (eggs) from the first father, resulting in two fathers being able to pass their genetic legacy on to offspring.

Applications may also lie in livestock breeding. Typically livestock are selected for favorable characteristics. But what if two males both have certain very favorable genetic traits? This technique could allow those strengths to be merged.

Last, but not least, the team's most controversial suggestion is that using a varied iPS technique, human oocytes (eggs) could be produced from a father's cells. This could lead to two men being able to synthetically reproduce, certainly a controversial technology. The only question left is whether two females could be made to reproduce as well? We'll have to wait and see for future studies on that topic.

"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov